Abstract
BackgroundTyrosine kinase inhibitor-induced hypothyroidism is associated with favorable survival in patients with various cancers. We aimed to investigate the incidence of regorafenib-induced hypothyroidism and assess its prognostic value in patients with metastatic or unresectable colorectal cancer (CRC) receiving regorafenib. MethodsThis study included 68 patients with metastatic or unresectable CRC refractory to standard therapies from Asan Medical Center between 2014 and 2016. Regorafenib (160mg/day on days 1–21, following a 7-day break) was administered. ResultsThe median patient age was 58 (range, 26–72) years, and 61.8% of patients were male. Among the 68 patients, 50 (73.5%) showed hypothyroidism [subclinical hypothyroidism in 39 (57.4%) and symptomatic hypothyroidism in 11 (16.2%)]. Thyroid hormone replacement relieved fatigue, and the thyroid stimulating hormone level stabilized in patients with symptomatic hypothyroidism. Overall, the objective response rate (ORR) and disease control rate (DCR) were 7.4% and 70.6%, respectively, and were significantly higher in patients with symptomatic or subclinical hypothyroidism than in those with a euthyroid status (ORR: 27.3% vs. 5.1% vs. 0.0%, P=0.001; DCR: 100% vs. 76.9% vs. 38.9%, P=0.001). Median progression-free survival (PFS) and overall survival (OS) were longer in patients with symptomatic hypothyroidism than in those with subclinical hypothyroidism (median PFS: 9.1 vs. 3.8 months, P=0.018; median OS: 19.2 vs. 9.4 months, P=0.012) or those with a euthyroid status (median PFS: 9.1 vs. 1.8 months, P<0.001; median OS: 19.2 vs. 4.7 months, P=0.001). The occurrence of symptomatic hypothyroidism was a significant protective factor for PFS [hazard ratio (HR)=0.37, P=0.006] and OS (HR=0.35, P=0.007). ConclusionsAs regorafenib-induced hypothyroidism occurs frequently and is associated with better survival in patients with metastatic CRC receiving regorafenib, active monitoring of the thyroid function status is necessary during regorafenib treatment. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.
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